Self-locking screw-threaded element



Nov. 27, 1951 w. c. BEACH 2,576,438

' SELF-LOCKING SCREW-THREADED ELEMENT Filed May 10, 1946 IN VEN TOR. VVLL/IRD GEE/40H BY ATTORNEY Patented Nov. 27, 1951 SELF-LOCKING SCRW-THREADED ELEMENT Willard 0. Beach, Montville, N. J. Application May10, 1946, Serial No. 668,915

3 Claims.

I The present invention relates to a self-locking screw threaded elementof the type which enters an internally threaded blind hole. Such elementmay take the form of a stud, machine-screw or the like, or may take anyspecial form such as a hook, hanger, pintle or any other device whichincludes an externally threaded cylindrical body which it is desired tolock into an internally threaded blind hole.

The primary object of the invention is to provide a self-lockingscrew-threaded element in which the threaded portion adapted to beentered into an internally threaded blind hole has an uninterrupted oruniform lead and which is distorted for locking purposes only when theentering end thereof is seated against the bottom of the blind hole. Theelement thus may be re.- peatedly screwed into place and removed withoutdamage to its threads or the threads of the blind hole, such operationsbeing free of any unusual effort except at the time of locking.

Other and further objects in part will be obvious and in part willbecome apparent from the following description and the drawings forminga part of the present specification.

In the drawings:

Fig. 1 is an elevation of a stud embodying the invention;

Fig. 2 is an enlarged elevation of the entering end of the stud shown inFig. 1;

Fig. 3 is an end elevation taken in the plane which includes the line3-3 of Fig. 1 and looking in the direction of the arrows;

Fig. 4 is a section along the line 4-4 of Fig. 1; and

Fig. 5 shows the stud of Fig. 1 in use.

Referring now to the drawings, a preferred form of the invention isdisclosed as embodied in a threaded element generally indicated at M.For purposes of illustration the threaded element may comprise a stud ofthe type which is provided with a continuous external thread l2. Aportion of the thread is intended to be entered into an internallythreaded blind hole in a suitable body (see Fig. 5) and it will beunderstood that the present invention relates only to such portion. Thusit is immaterial to the present invention whether the portion of thethreaded element l0 extending outside a body such as 14 is provided witha continuation of the thread l2 or with a different thread or with ahead. shank or other element such as a hook and the like.

Thelower end of the element I0, as viewed in Fig. l, is the entering endthereof. Adjacent the verse slots such as the slots l6 and I8 showninthe drawings. If only one slot is provided it will be formed in theelement to in the position occupied by the slot [6. If two slots areprovided, the second slot will be formed in the position 00'- cupied bythe slot l8. If more than two slots are provided, the third and othersuccessive slots will enter the body of the threaded element ID fromalternate sides and will be spaced from one another in the mannerillustrated in connection with the slots [6 and H3.

The slot IE enters the body of the threaded ele ment l0 on the lefthandside thereof as viewed in Fig. 1 and extends substantially normal to theaxis of the body to and somewhat beyond said axis as shown, for example,in Fig. 4. The slot 16 thus cuts slightly more than halfway through thethickness of the threaded element l0. It is important that the slotextend beyond the axis but it will be realized that it cannot extend toogreat a distance beyond said axis without so severely weakening thethreaded body as to render it impractical. It is preferred that the slot16 extend beyond the axis a distance roughly equal to one-fourth orone-fifth of the radius of the core of the threaded body. The exactdistance will be determined in some measure at least by thecharacteristics of the metal or other material from which the threadedelement may be formed and the proportions illustrated and discussedherein have been found suitable for use in a threaded element made fromiron. The slot l8 enters the body of the threaded element I0 -from theside thereof opposite the open end of slot I6. Thus in Fig. l the slotl8 enters the threaded body I0 from the righthand side thereof. The slotl8 and any additional slots which might be provided are also extendedbeyond the axis of the threaded body as in the case ofv the slot l6.

As shown in Fig. 4, the slots I6 and I8 overlap throughout the diameterof the threaded body [0. It has been found preferable to provide thethreaded element with two slots such as the slots [6 and I8, theoverlapping thereof as shown in Fig. 4 making it certain that the regionof the threaded element It! adjacent such slots will be distorted by themeans to be described hereinbelow to an extent to insure extremely firmlooking of the threaded element in a blind hole.

The entering end of the threaded element I0 is provided with a nose 20the apex of which is eccentrically disposed relative to the axis of thethreaded body ID. The nose 20 is shown in end elevation in Fig. 3 and itwill be observed that it is generally conical in shape and that thesurface to the right of the apex slopes more gently toward the axis thandoes the surface to the left of the apex. The particular conformation ofthe nose is not of critical importance to the present invention but itis important that a relatively sharp apex be provided and that this apexbe positioned in vertical alignment with substantially the mid-point inthe depth of the slot H3. Thus pressure exerted upon the nose 20 willtend to cantlthe portion of the threaded body extending downwardly ofthe slot l6 and thus will tend to close the slot Hi.

When the threaded element I is entered into an internally threaded blindhole as illustrated in the body M (Fig. 5), the uniform anduninterrupted pitch of the threads will permit the body to be easilyturned and brought substantially to the bottom of the hole. In suchoperation no undue resistance will be met nor will any damage be done tothe threads on the element I0 or within the blind hole. When the nose 28impinges upon thebottom 22 of the blind hole and continued turningeifort is applied to the threaded .element It, a relatively heavypressure will be exerted between the nose 2B and the bottom 22. Theforces set up upon impingement will be such as to tend to close the slotlfi andthus to throw the threads on'the'extreme end of the element .outof alignment with the'remaining threads thereon. This action will bringabout a very effective locking engagement between the body element [0and the body l4.

A single slot such as I B will bring about a looking action entirelysatisfactory for many purposes. However, a much more effective lockingaction is achieved if two slotsare provided. In some instances itis'desirable to provide more than two slots although the increasedlocking efficiency thus achieved is not so marked as the increaseachieved in providing two slots. When two slots are provided, thepressure exerted between thenose andthe bottom 22 of the blind hole willtend not only to close the slot l6 but alsoto close the slot l8 inasmuchas downward movement of the element 18 as it is turned is resisted firstby the nose 2!) impinging-uponthe bottom 22 which results inpartiallyclosing the slot 16, and, second,by the uncut portion of theelement [0 extending verticallybelowthe slot [8.

It has been found particularlyimportant to provide an. adequate extentof thread between the entering end of the element .l0 and-the slot [6 aswell as between the slot lfi and theslot [8. Obviously, if too littlemetal is left, the .device will be structurally weak and furthermore,there will notbe sufiicient thread to .bring about an effective lockingaction. .It has been found that about two full turns of thread must belef-t'beyond the slot ifiand between the slot J6and the slot 18. Ifsubstantially more than 'two full .turns is left in either of theseportions, the device will be toostiif and will, not be likely to lookwithout undue effort, and it may be ex- .tremely difficult .to .removethe .threaded element if itmight be desired-tondorso. If .two full turns.of threadare left in theportions indicated, it will be foundthatefiectivelocking will occur without undue effort .and it will .be..fo.und that the threaded element 10 maybe removed from the body Hi byapplying a. moderate turningforcefor a short time after which ,the nose2!) will he re- ,moved from contact with the bottom-22. When thisoccurs, the element 10- mayberemovedfrom the body 14 without anydifficulty inasmuch as the distortion-incident tolocking is almostwholly temporary.

The-operationofllocking the threaded element 4 7 ID in a blind hole isindependent of the particular shape of the bottom of such hole. Ingeneral, such holes will have a conical bottom resulting from theconformation of a drill and for this reason a conical bottom 22 has beenillustrated herein. However, it is apparent that the nose 20 willoperate with equal effectiveness when *brought into contact withiafiatsurface or any other shape of surface ordinarily existing at the bottomof a blind hole.

In Fig. 5 the threaded element It! has been shown turnedinto the body I4and locked therein by bringing the nose 20 into engagement with thebottom 22. The slots l6 and i 8 have been shown as partially closed andas a result of such closing, the portion of the threaded element in theregion of the slots 16 and [8 has been distortedinto such shape as tolock the element It! in the body I 4. The threaded element ID has beenshown as a stud and to illustrateone use of suchastud there-isshown asecond body-24 secured againstthe body I4. The body .24 is providedwithasmOOth hole 26 through whichthe stud to projects and a nut -orother suitable fastening device is shown threaded upon thezfree .end ofthe stud l0. v

The above detailed disclosure of preferred forms of the invention andthe disclosure of a specific embodiment thereof .is for the .purpose ofcomplying with the patent statutes, anditwill be understood thatmodifications and variations may be resorted to'by those skilled in theart without departing from the scope .of the appended claims.

I claim:

l. A self-locking screw-threaded element'lhaving a screw-threadedportion adapted tobe. entered into an internally threadedblind hole,.said threaded portion having a .uniform lead and having adjacent theentering en'd'thereof aplurality of slots extending .transverselyoftheraxis of rotationof said threaded portion, eachslot entering saidthreaded portion on onesideo'f said axis and extendingiro'm. saidsideacrossand beyond said axis and said slots overlapping substantiallythroughout the .diameter .of.-saidelement, there being at least onecomplete turniof thread between the entering end of said element and theslot nearest said end and between adjacent slots, and .a nose .formed onthe entering end of said element'the apex of saidnose beingeccentrically disposed vrelative to said axis and positioned on thesidethereof from which the slot nearest said end enters said element,said nose being adapted toimpinge uponthe'bottom of said blind hole tocause distortion of said threaded portion in the region'ofsaid slots.

2. A self-lockingscrevhthreadedelement .having a screw -threaded'portionadapted to beentered'into an internally threaded blind hole,-s-aidthreaded portion having a uniformlead and-having adjacent the endthereof a plurality of slots extending transversely of the axis of.rotation of saidthreaded portion, each rslotentering said threadedportion on one side-of said axis and extending fromsaidsideacrosswandbeyond said axis and said s10ts overlapping substantially throughout.the diameter of .saidlelement, .there beingsubstantially two .turns ofthread between the entering end of .said element and the .slot nearestsaid end .and-betweenadiacent slots, and a nose on .theentering .endofsaid element said nose being eccentrically disposed relative to saidaxis and positioned on the side thereof from which theslotnearestisaidend enters said ele- 5 ment, said nose being adapted toimpinge upon the bottom of said blind hole to cause distortion of saidthreaded portion in the region of said slots.

3. A self-locking screw-threaded element having a screw-threaded portionadapted to be entered into an internally threaded blind hole, saidthreaded portion having a uniform lead and having adjacent the endthereof a plurality of slots extending transversely of the axis ofrotation of said threaded portion, each slot entering said threadedportion on one side of said axis and extending from said side across andbeyond said axis and said slots overlapping substantially throughout thediameter of said element, there being substantially two turns of threadbetween the entering end of said element and the slot nearest said endand between adjacent slots, and a nose on the entering end of saidelement, said REFERENCES CITED The following references are of record inthe file of this patent:

UNITED STATES PATENTS Number Name Date 1,861,833 Bergstrom June 7, 19322,007,171 Bergstrom July 9, 1935 2,224,659 Stoll Dec. 10, 1940 2,243,515Van Sant May 27, 1941 2,386,897 Johnson Oct. 16, 1945

